The veteran host, who had co-anchored Today for 20 years and was earning a reported $20 million a year, apologized on Thursday, saying in a statement, "There are no words to express my sorrow and regret for the pain I have caused others by words and actions. To the people I have hurt, I am truly sorry."

NBC News Firing: NBC News Chairman Andy Lack sent the following memo to NBC News staffers on Wednesday, the day Lauer's termination was announced:

"On Monday night, we received a detailed complaint from a colleague about inappropriate sexual behavior in the workplace by Matt Lauer. It represented, after serious review, a clear violation of our company's standards. As a result, we've decided to terminate his employment. While it is the first complaint about his behavior in the over 20 years he's been at NBC News, we were also presented with reason to believe this may not have been an isolated incident.

Our highest priority is to create a workplace environment where everyone feels safe and protected, and to ensure that any actions that run counter to our core values are met with consequences, no matter who the offender.

We are deeply saddened by this turn of events. But we will face it together as a news organization — and do it in as transparent a manner as we can."

Multiple Accusations: As Lack had said, NBC News officials were presented with reason to believe that the employee's complaint against Lauer "may not have been an isolated incident." Indeed, more sexual misconduct allegations were reported after his firing was announced. E! News has not confirmed the accusers' accounts and Lauer has not commented on any specific allegations.

Variety reported that it had carried out a two-month investigation of Lauer, talking to three women who identified themselves as victims of sexual harassment by him as well as dozens of current and former staffers. The New York Times reported that on Wednesday, after Lauer's firing, NBC "received at least two more complaints" related to him. None of the accusers who spoke to either outlet have identified themselves by name and it is unclear if any were interviewed by both publications.

NBC officials confirmed to NBC News that two more Lauer accusers came forward on Wednesday. No further details were given.

Sexual Assault One of the accusers who made a complaint about Lauer after his firing is a former Today producer who said the host allegedly summoned her to his office in 2001, locked the door and sexually assaulted her, The New York Times said.

Secret Button? Variety reported that Lauer's office was located in a secluded space and that he had a button under his desk that allowed him to lock his door from the inside without getting up, which "allowed him to welcome female employees and initiate inappropriate contact while knowing nobody could walk in on him," the outlet said, citing two women who say they were sexually harassed by him.

The New York Times reported cited former NBC employees as saying the button was a regular security measure installed for high-profile employees.

The accuser who talked to the newspaper and made a complaint on Wednesday about Lauer told the outlet that he had asked her to his office to discuss a story and locked the door after she sat down. She said Lauer allegedly asked her to unbutton her blouse, which she did, then had sex with her. She said she passed out with her pants pulled halfway down and woke up on the floor. She said Lauer allegedly had his assistant take her to a nurse.

The accuser, who left her job a year later, said the host never made an advance toward her again and never mentioned what occurred. She said she did not report the episode to NBC at the time because she believed she should have done more to stop him.

The woman also said that Lauer allegedly made inappropriate comments to her in the late '90s, after she started her job, such as asking whether she had ever cheated on her husband. She also said that he sat uncomfortably close to her as they traveled to an airport and told her "You're no fun" when she moved away.

Indecent Exposure?Variety said Lauer allegedly summoned a female colleague to his office, dropped his pants and exposed himself to her, adding that after she declined to do anything, he reprimanded her for not engaging in a sexual act.

Sex Toy? Variety said that as the co-host of Today, Lauer allegedly once gifted a colleague a sex toy and included an explicit note about how he wanted to use it on her.

Sexting?Page Sixreported after Lauer's firing that he allegedly sent female staffers and a young intern at NBC lewd messages and revealing pictures. The outlet said one of the woman was the person whose complaint prompted the host's termination.

F--k, Marry or Kill? Variety reported Lauer would allegedly sometimes quiz female producers about who they'd slept with, offering to trade names, and also play with both male and female colleagues a "F—, Marry, or Kill" game, in which he would identify the female co-hosts that he'd most like to sleep with.

The New York Times said two former Today employees recalled colleagues playing the game, but did not name Lauer.

Hotel Visits? Variety reported that while he was covering the Olympics in various cities over the years, Lauer would invite female NBC employees to his hotel room late at night.

Lack had said in his statement that the complaint made by the woman who reported Lauer's alleged inappropriate behavior at the Sochi Olympics marked "the first complaint about his behavior in the over 20 years he's been at NBC News."

"There was never a complaint about Matt. There was never a suggestion of that kind of deviant or predatory behavior. There was never even a whisper of it."," Jeff Zucker, a former Today show producer who later became CEO of NBCUniversal and spent 25 years at the network before becoming president of CNN in 2013, said during the IGNITION 2017 conference on Thursday.

"I've known Matt for 25 years and I didn't know this Matt," he said, "It's incredibly, incredibly heartbreaking."